secession Look up secession at Dictionary.com
1530s, from L. secessionem (nom. secessio), from pp. stem of secedere "secede," from se- "apart" (see secret) + cedere "to go" (see cede). Originally in a Roman historical context, "temporary migration of plebeians from the city to compel patricians to address their grievances;" modern use in reference to religious or political unions dates from 1650s.